It is known from U.S. Pat. No. 4,528,225 that the foil tube can be manufactured by unwinding a band-shaped flat foil, which has been provided unilaterally with a connecting layer, from a stock supply, and bending it in the longitudinal direction to form the tube in such a way that the connecting layer is located on the outside, and the longitudinal sides of the longitudinal edges are located opposite one another, after which a strip, which is capable of forming a connection or which is provided with a connecting layer, is placed in the longitudinal direction over both longitudinal edges and is connected to them. The completed tube is then rolled up and used at a subsequent point in time and at another location for the manufacture of packs for a product in portions.
The connection of the longitudinal edges of the foil band by means of a connecting strip permits the use of a foil, which has been provided only unilaterally with a connecting layer, and thereby solves a problem that arises during the process, which is known from EP-B-105 558 and EP-B-177 993, namely that longitudinal edges are connected to one another in a mutually overlapping manner by means of hot sealing. This is because the foil must be bilaterally sealable in order to ensure an air-tight and liquid-impermeable sealing seam because the outer surface comes into contact with the inner surface when overlapping the foil's edges.
In such cases, use is therefore made of triple layer foils comprising a middle supporting foil and bilateral sealing layers. Such foils are not only expensive in terms of manufacture, but they also have the additional disadvantage that the raw sausage composition, which is introduced into the foil tube during sausage manufacture, does not adhere adequately to the sealing layer, so that the product, which is to be packaged, becomes detached during the cooking process and bubbles are formed that become filled with fatty or gelatin material from the raw sausage composition. This is unwelcome for optical reasons. Thus the foil's surface, which faces the product that is to be packaged, is treated mechanically or chemically in order to increase the adhesion of the raw sausage composition. Thus it is provided according to DE 196 18 172 A1, for example, that the (subsequent) inner surface of the tubular packaging casing be treated by a corona in order to ensure the adhesion of the raw sausage composition to the inner surface of the foil tube. However, this all requires additional expense.
On the other hand, no treatments of the foil tube's inner surface are possible in the case of its manufacture according to U.S. Pat. No. 4,528,225 that was outlined previously, whereby such treatments would exert mechanical or taste-related effects on the product that is to be packaged, i.e., a raw sausage composition in particular, and whereby the effects exerted thereon would improve, for example, the adhesion of the raw sausage composition or release flavoring materials to the product that is to be packaged. This is because such treatments, which usually take place in the form of the application of coatings, are destroyed by rolling up the completed foil tube and have in addition a non-permanent existence.